1. Field of the Invention
The present invention relates to a package structure for light-emitting diodes (LEDs); more particularly to a package structure capable of reducing the temperature difference between the LED chips disposed on a central portion and the LED chips disposed on a peripheral portion.
2. Description of Related Art
Typically, for the multi-chip package structure, the temperature of the light-emitting chips disposed on the central region of substrate is higher than that of the light-emitting chips disposed on the peripheral region of the substrate. This temperature difference causes the forward bias of the light-emitting chips disposed on the central region to be less than that of the light-emitting chips disposed on the peripheral region. Hence, more current is flowed to the central region that reduces the reliability of the chips on the central region. Moreover, the higher temperature associated with the chips disposed on the central region also reduces the light emission efficiency of those chips. In other words, the chips disposed on the central region are less bright in comparing to the chips disposed on the peripheral region.
Thus, how to enhance heat dissipation for the central region of the substrate to reduce the abovementioned temperature difference is an important task.